#define VOXMODEL_IMPORTED

using Godot;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text;


[GlobalClass]
public partial class VoxModel : Resource
{
    [Export]
    public VoxSubmodel[] submodels;
    [Export]
    public Color[] palette;

    public IEnumerable<(Vector3I, Color)> GetVoxels(int submodelIndex)
    {
        foreach (var xyzi in submodels[submodelIndex].xyzi.Chunk(4))
        {
            yield return (new(xyzi[0], xyzi[1], xyzi[2]), palette[xyzi[3]]);
        }
    }

    public static VoxModel Load(string path)
    {
        using var file = FileAccess.Open(path, FileAccess.ModeFlags.Read);

        var magic = Encoding.ASCII.GetString(file.GetBuffer(4));
        Debug.Assert(magic == "VOX ");

        var versionNum = file.Get32();
        //GD.Print($"Loading vox file, Ver: {versionNum}");

        var mainChunkId = Encoding.ASCII.GetString(file.GetBuffer(4));
        //GD.Print($"Main chunk id is {mainChunkId}");

        var mainChunkContentSize = file.Get32();
        var mainChunkChildrenSize = file.Get32();

        file.Seek(file.GetPosition() + mainChunkContentSize);

        var submodels = new List<VoxSubmodel>();
        Color[] palette = null;

        while (file.GetPosition() < file.GetLength())
        {
            if (file.EofReached()) break;

            var chunkId = Encoding.ASCII.GetString(file.GetBuffer(4));
            //GD.Print($"Reading chunk: {chunkId}");
            var contentSize = file.Get32();
            var childrenSize = file.Get32();

            switch (chunkId)
            {
                case "PACK":
                    submodels.Capacity = (int)file.Get32();
                    //GD.Print($"This file cotains {submodels.Capacity} submodels");
                    break;
                case "SIZE":
                    submodels.Add(new VoxSubmodel()
                    {
                        width = (int)file.Get32(),
                        height = (int)file.Get32(),
                        length = (int)file.Get32(),
                    });
                    break;
                case "XYZI":
                    var model = submodels.Last();
                    var count = file.Get32() * 4;
                    model.xyzi = new byte[count];
                    for (int i = 0; i < count; i++)
                    {
                        model.xyzi[i] = file.Get8();
                    }
                    break;
                case "RGBA":
                    palette = new Color[256];
                    for (int i = 0; i < 255; i++)
                    {
                        palette[i + 1] = new Color(ToRGBA(file.Get32())).SrgbToLinear();
                    }
                    break;
                default:
                    file.Seek(file.GetPosition() + contentSize + childrenSize);
                    break;
            }
        }

        palette ??= DEFAULT_PALETTE.Select(x => new Color(ToRGBA(x)).SrgbToLinear()).ToArray();

        return new VoxModel()
        {
            submodels = [.. submodels],
            palette = palette,
        };
    }

    private static uint ToRGBA(uint agbr)
    {
        var a = agbr & 0xff000000;
        var b = agbr & 0xff0000;
        var g = agbr & 0xff00;
        return (agbr << 24) | (g << 8) | (b >> 8) | (a >> 24);
    }

    private static uint BinRev(uint x)
    {
        x = ((x & 0xaaaaaaaa) >> 1) | ((x & 0x55555555) << 1);
        x = ((x & 0xcccccccc) >> 2) | ((x & 0x33333333) << 2);
        x = ((x & 0xf0f0f0f0) >> 4) | ((x & 0x0f0f0f0f) << 4);
        x = ((x & 0xff00ff00) >> 8) | ((x & 0x00ff00ff) << 8);
        return (x >> 16) | (x << 16);
    }

    private static uint[] DEFAULT_PALETTE = {
        0x00000000, 0xffffffff, 0xffccffff, 0xff99ffff, 0xff66ffff, 0xff33ffff, 0xff00ffff, 0xffffccff, 0xffccccff, 0xff99ccff, 0xff66ccff, 0xff33ccff, 0xff00ccff, 0xffff99ff, 0xffcc99ff, 0xff9999ff,
        0xff6699ff, 0xff3399ff, 0xff0099ff, 0xffff66ff, 0xffcc66ff, 0xff9966ff, 0xff6666ff, 0xff3366ff, 0xff0066ff, 0xffff33ff, 0xffcc33ff, 0xff9933ff, 0xff6633ff, 0xff3333ff, 0xff0033ff, 0xffff00ff,
        0xffcc00ff, 0xff9900ff, 0xff6600ff, 0xff3300ff, 0xff0000ff, 0xffffffcc, 0xffccffcc, 0xff99ffcc, 0xff66ffcc, 0xff33ffcc, 0xff00ffcc, 0xffffcccc, 0xffcccccc, 0xff99cccc, 0xff66cccc, 0xff33cccc,
        0xff00cccc, 0xffff99cc, 0xffcc99cc, 0xff9999cc, 0xff6699cc, 0xff3399cc, 0xff0099cc, 0xffff66cc, 0xffcc66cc, 0xff9966cc, 0xff6666cc, 0xff3366cc, 0xff0066cc, 0xffff33cc, 0xffcc33cc, 0xff9933cc,
        0xff6633cc, 0xff3333cc, 0xff0033cc, 0xffff00cc, 0xffcc00cc, 0xff9900cc, 0xff6600cc, 0xff3300cc, 0xff0000cc, 0xffffff99, 0xffccff99, 0xff99ff99, 0xff66ff99, 0xff33ff99, 0xff00ff99, 0xffffcc99,
        0xffcccc99, 0xff99cc99, 0xff66cc99, 0xff33cc99, 0xff00cc99, 0xffff9999, 0xffcc9999, 0xff999999, 0xff669999, 0xff339999, 0xff009999, 0xffff6699, 0xffcc6699, 0xff996699, 0xff666699, 0xff336699,
        0xff006699, 0xffff3399, 0xffcc3399, 0xff993399, 0xff663399, 0xff333399, 0xff003399, 0xffff0099, 0xffcc0099, 0xff990099, 0xff660099, 0xff330099, 0xff000099, 0xffffff66, 0xffccff66, 0xff99ff66,
        0xff66ff66, 0xff33ff66, 0xff00ff66, 0xffffcc66, 0xffcccc66, 0xff99cc66, 0xff66cc66, 0xff33cc66, 0xff00cc66, 0xffff9966, 0xffcc9966, 0xff999966, 0xff669966, 0xff339966, 0xff009966, 0xffff6666,
        0xffcc6666, 0xff996666, 0xff666666, 0xff336666, 0xff006666, 0xffff3366, 0xffcc3366, 0xff993366, 0xff663366, 0xff333366, 0xff003366, 0xffff0066, 0xffcc0066, 0xff990066, 0xff660066, 0xff330066,
        0xff000066, 0xffffff33, 0xffccff33, 0xff99ff33, 0xff66ff33, 0xff33ff33, 0xff00ff33, 0xffffcc33, 0xffcccc33, 0xff99cc33, 0xff66cc33, 0xff33cc33, 0xff00cc33, 0xffff9933, 0xffcc9933, 0xff999933,
        0xff669933, 0xff339933, 0xff009933, 0xffff6633, 0xffcc6633, 0xff996633, 0xff666633, 0xff336633, 0xff006633, 0xffff3333, 0xffcc3333, 0xff993333, 0xff663333, 0xff333333, 0xff003333, 0xffff0033,
        0xffcc0033, 0xff990033, 0xff660033, 0xff330033, 0xff000033, 0xffffff00, 0xffccff00, 0xff99ff00, 0xff66ff00, 0xff33ff00, 0xff00ff00, 0xffffcc00, 0xffcccc00, 0xff99cc00, 0xff66cc00, 0xff33cc00,
        0xff00cc00, 0xffff9900, 0xffcc9900, 0xff999900, 0xff669900, 0xff339900, 0xff009900, 0xffff6600, 0xffcc6600, 0xff996600, 0xff666600, 0xff336600, 0xff006600, 0xffff3300, 0xffcc3300, 0xff993300,
        0xff663300, 0xff333300, 0xff003300, 0xffff0000, 0xffcc0000, 0xff990000, 0xff660000, 0xff330000, 0xff0000ee, 0xff0000dd, 0xff0000bb, 0xff0000aa, 0xff000088, 0xff000077, 0xff000055, 0xff000044,
        0xff000022, 0xff000011, 0xff00ee00, 0xff00dd00, 0xff00bb00, 0xff00aa00, 0xff008800, 0xff007700, 0xff005500, 0xff004400, 0xff002200, 0xff001100, 0xffee0000, 0xffdd0000, 0xffbb0000, 0xffaa0000,
        0xff880000, 0xff770000, 0xff550000, 0xff440000, 0xff220000, 0xff110000, 0xffeeeeee, 0xffdddddd, 0xffbbbbbb, 0xffaaaaaa, 0xff888888, 0xff777777, 0xff555555, 0xff444444, 0xff222222, 0xff111111
    };
}
